翻译《如果你跌入黑洞，会发生什么？》

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　　来源：BBC EARTH

　　What would happen if you fell into a black hole?

　　By Lucy Freeman

　　The black hole; fascinating, mysterious, deadly.

　　There is something chilling about the phrase “black hole”. It suggests nothingness, incites feelings of danger; and alludes to something that could pull us in and entrap us. A place where time means nothing, with mind-blowing qualities that we struggle to grasp.

　　So what is a black hole? How can something that is essentially an “invisible nothing” be so important and so powerful? It’s all about gravity, and the pull of black holes, that makes them so intriguing.

　　如果你跌入黑洞，会发生什么？

　　露西•弗里曼

　　黑洞：着迷的，神秘的，致命的。

　　“黑洞”，这个短语让人打冷颤，它表示虚无，引起危险的感觉。它表示可以把我们拉进去，使我们陷进去的某样东西。这是一个没有时间意义的地方，引起无限遐思而我们想努力抓住的地方。

　　于是，黑洞是什么？某样东西，本质上是看不见的虚无，却是如此的重要，如此的有力量吗？这一切全都是引力，即黑洞的拉力，使得它们有如此的吸引力。

　　How are they made?

　　Black holes are forged from the small, dense, remnant cores of dead stars. If the core's mass is more than about three times the mass of the Sun, the force of gravity overwhelms all the other forces, the remnant collapses and produces a black hole.1

　　Black holes are objects with extreme density, and the amount of mass they have means they have so much gravitational pull that even light gets trapped. Astronomers believe that most spiral and elliptical galaxies have black holes at their centres.2

　　There are three types of black hole. Stellar-mass black holes are the smallest; between 1 and 100 times the mass of the Sun. They form after the centre of a large star collapses, causing a supernova (the explosion of a star).3 The largest, known as supermassive black holes, can have masses that are millions if not billions of times the mass of the Sun. It is thought that this type of black hole reaches its enormous size by merging with other black holes, as well as by subsuming stars.4 Intermediate-mass black holes are a third category that – as the name suggests – falls somewhere between the previous two. They’re still a bit of a mystery, with only a few having been discovered, but they’re each believed to have a mass of between 100 and 100,000 Suns. It is thought that these are the black holes that merge to form the supermassive variety.5

　　它们是怎样形成的

　　黑洞形成于死亡星星的小而密集的残核。如果核心的质量大致是太阳质量的三倍以上，引力就超过了所有的力量，残核就坍塌，就产生了黑洞。

　　黑洞是密度极高的物体，它们所具有的质量表示它们的引力是如此之大，甚至就是光也被吸引进去了。天文学家相信，大多数螺旋星系和椭圆星系的中心都有黑洞。

　　黑洞有三种类型。恒星质量的黑洞是最小的，在太阳质量的1倍到100倍之间。它们在大星中心坍塌之后形成，变为一颗超新星。最大的黑洞，是超质量的黑洞，其质量即使没有太阳质量的数十亿倍，也有它的数百万倍，有人认为，这种类型的黑洞是通过和其他黑洞合并或通过吸纳其他星星而变得巨大。中等质量的黑洞是第三类——顾名思义——介于前两类之间。它们仍然是一个迷，只发现了少数，但它们被认为其质量是在100颗到100,000颗太阳之间。有人认为它们是合并而成的超大质量的黑洞。

　　Why are they important?

　　Not only do black holes explain the seemingly chaotic movements of some stars and help make sense of our galaxy, but they represent a new realm of physics for scientists. Einstein’s theory of general relativity6 states that matter warps time and space, creating what we call gravity – and black holes are incredibly dense conglomerations of matter, hence their incredible gravitational pull. But from there on in – quite literally – they put Einstein’s theory to the test.

　　When we look at the centre of a black hole – the ‘singularity’ – it gets complicated. The forces at play there are so immense that science can’t agree about what happens next. Einstein’s general relativity says that when matter is pulled into a black hole, its information is destroyed – but quantum mechanics says that cannot happen.

　　As a result, black holes are an incredible theoretical playground for astrophysicists and mathematicians, attempting to reconcile the two theories. From general relativity to quantum physics and string theory, black holes offer experts a testing ground for fundamental theories that explain how the universe operates.7

　　它们为什么重要？

　　黑洞不仅解释了一些星星看似混乱的运动，并帮助我们理解了银河系，而且它们还为科学家展示了一个新的物理领域。爱因斯坦的广义相对论认为，物质曲扭了时间和空间，创造了我们称之为的引力。而黑洞是难以置信的致密物质聚集体，因而具有难以置信的引力拉力。但从那时起——照直说来——它们（指黑洞——译者注）就验证了爱因斯坦的理论。

　　当我们看黑洞的中心——奇点时，它就变得复杂了。那里，起作用的力量如此强大，以至于科学对下一步发生的事说法不一。爱因斯坦的广义相对论说当物质被拉入黑洞时，其信息就破坏了——但量子力学说这是不会出现的

　　因此，黑洞是天体物理学家和数学家奇妙的理论游乐场，还试图调和这两种理论。从广义相对论到量子物理学和弦理论，黑洞给专家提供了基础理论的试验场，这些理论解释宇宙是怎样运行的。

　　Can we see them?

　　Black holes have such an immense gravitational pull that not even light can escape, so they cannot be seen directly. As a result, huge radio telescopes and gravitational wave detectors are used instead of conventional telescopes.

　　In 1915, Albert Einstein theorized that when objects move through space, they create waves in spacetime (a concept which fuses space and time)8 around them, just like ripples moving across the surface of a pond. Then, a century later in 2015, he was proved correct when gravitational waves were detected for the first time by researchers at the Laser Interferometer Gravitational-Wave Observatory (LIGO). This was caused by two black holes colliding, 1.3 billion years earlier!9

　　Black holes can be located by the effect they have on what’s around them – they suck in gas, dust and stars, which becomes superheated and emits radiation that can then be ‘seen’ as a heat image. In April 2019, an image of a black hole and its shadow in the galaxy Messier 87, part of the Virgo galaxy cluster, was captured for the first time using the Event Horizon Telescope, an array of eight ground-based radio telescopes specifically designed to capture images of a black hole. The image shows a bright ring around a black hole 6.5 billion times more massive than the Sun, 55 million light years from Earth. This ‘halo’ is actually a visualisation of the heat given out by hot gas swirling around the event horizon – the very edge of the black hole – as it’s being pulled in.10

　　我们能看到它们吗？

　　黑洞有巨大的引力，就是光也逃不脱。所以直接看不到它们。因而巨大的射电望远镜和引力波探测器被用来代替常规的望远镜。

　　1915年，阿尔伯特•爱因斯坦提出了一种理论：当物体在空间移动时，它们周围的时空就产生了引力波（一种融合了空间和时间的观念），这很像水塘表面的小波浪。一个世纪后的2015年，引力波首次由激光干涉仪引力波观测台（LIGO）的研究人员检测到，证明他是正确的，这是13亿年前两个黑洞碰撞时产生的。

　　黑洞的位置可以视他们对周围情况的影响而定——他们吸收气体，尘埃和星星，这些气体，尘埃和星星变得超级热而释放出可以看得到热图像的辐射。2019年4月，梅希焉星系中的黑洞及其影子，这是室女座星系团的一部分，首次被视界望远镜抓拍到，视界望远镜是一个方阵，由8个地面射电望远镜组成。专门设计用来抓拍黑洞的图像。该图像显示了黑洞四周有一个很亮的光环，黑洞的质量是太阳的56亿倍，距地球有5500万光年。这个光环实际上是由围绕事界旋转的热气体产生的可视化的热——黑洞边缘——因为它被拉了进来。

　　What would happen if you fell into one?

　　So, the big question – what would happen if you fell into a black hole? Well, the prognosis isn’t great, to be truthful, whichever sort of black hole you picked.

　　If you leapt heroically into a stellar-mass black hole, your body would be subjected to a process called ‘spaghettification’ (no, really, it is). The black hole’s gravity force would compress you from top to toe, while stretching you at the same time…thus, spaghetti.11

　　A supermassive black hole has a slightly less horrendous effect, so let’s imagine then that you opt for one of these to make your giant leap for mankind and scientific research.

　　Sagittarius A* (pronounced “Sagittarius A-star”, and abbreviated as Sgr A*) is a supermassive black hole at the heart of the Milky Way, believed to be around 44 million km across and containing approximately 4.31 million solar masses.12 It was discovered in 1974 by two astronomers, Bruce Balick and Robert L Brown, but remained unnamed until 1982.13

　　如果你跌入黑洞，会发生什么？

　　这样，一个大问题，如果你跌入黑洞，会发生什么、嗯，预测并不重要，说实在的，你选择了哪一种类型的黑洞

　　如果你勇敢地跳入一个恒星质量的黑洞，你的身体将经历一个称之为“意大利面条化”的过程（不，真是这样的），黑洞的引力会从头到脚压缩你，同时又把你拉伸，这就是面条化。

　　超质量黑洞有稍微弱一点的影响，所以让我们想象一下，你选择了其中一个，你就为人类和科学研究迈出了重大的一步。

　　人马座A（读作Sagittarius A-star，缩写为Sgr A）是银河系中心的一个超质量黑洞，被认为直径有4千4百万英里，大约含有431万个太阳质量。它是由两个天文学家在1974年发现的：布鲁斯•巴力克和罗伯特•布朗，但直到1982年才命名。

　　Your journey into Sagittarius A* itself would begin after you slip over the event horizon, the point of no return. You would be able to see out from inside, but no-one would be able to see you because any light would fall back on you. The good news is that although the gravitational pull is much stronger than smaller black holes, the stretching tidal force is less, meaning you won’t be turned into spaghetti. But the bad news is you wouldn’t be able to get out….14

　　…or could you? Well, your hope lies in the theory of “white holes”. Put simply, if a black hole sucks things in, then a white hole spits them out again – – and the two are connected via an inter-dimensional tunnel, known as a wormhole. Or, it’s also hypothesised, if you waited long enough, the black hole will turn into a white one, anyway. This process is thought to take billions of years, but there’s no reason to be disheartened. Why? Well, due to the intense gravitational forces within, time would be speeded up for you – so it would be over in a matter of milliseconds. Of course, at present, this is only a theory…15

　　If you want more proof of the inadvisability of swan-diving into a black hole, consider the ‘tidal disruption’ picked up by three NASA telescopes in 2014. It was caused by a star that had come too close to a black hole at the centre of a galaxy, about 290 million light years away. It was distorted, stretched, and shredded as it was sucked into the singularity, while the residue of the destroyed star was flung out in a ‘cosmic belch’. 16

　　你进入人马座A的旅行在你跌落到事界后开始,这是一个回不去的点。你在里头看得见外面，但没有人看得见你，因为任何光都会回落到你身上。好消息是，虽然引力要比小些的黑洞大很多，但拉伸的潮汐力较小，这表明你不会变成意大利面条，但坏消息是你出不去…。

　　…或说你能吗？嗯，你的希望依赖于“白洞”理论。简单说来，如果黑洞把东西吞了进去，而白洞又将它们吐了出来。不管在那个地方，两者通过跨维度的隧道连接起来，这就是虫洞，或者，也可以假设，如果你等得够久，黑洞不管怎样都会变成白洞。这个过程被认为需要数十亿年，但没有理由感到心灰意冷，为什么呢？因为内部强大的引力，对你来说，时间会加速——这样，它几毫秒钟就结束了。当然，眼下，这只是一种理论。

　　如果你想获得天鹅般跃入黑洞是不明智的更多证据，考虑一下美国国家航空航天局的三个望远镜观察到的“潮汐扰动”。它是由一颗过于靠近星系中心的黑洞的星星引起的，该黑洞有2亿9千万光年远。当它被吸入奇点时，它被曲扭，拉伸，碾碎，这颗被摧毁的星星的残余物又同时以宇宙喷涌的形式被抛出来。

　　Conclusion

　　Considering our galaxy alone holds 100m stellar-mass black holes – and that our own galaxy, the Milky Way, has a supermassive black hole at its centre so enormous that it would fit inside the orbit of Mercury17 – maybe it’s time we started to learn more about these enigmatic phenomena. At least, just in case we ever find ourselves about to fall into one.

　　Note

　　1. The Cores of Dead Stars, 2. Black Holes at the Centre of Galaxies, 3. Stellar-mass black holes, 4. Supermassive Black Holes Really Are Super-Massive, 5. Intermediate-Sized Black Holes, 6. Einstein's theory of general relativity 7. General Relativity vs Quantum Theory, 8. Spacetime definition, 9. Gravitational Waves Detected, 10. Black hole 'halo', 11. Spaghettification, 12. Sagittarius A*, 13. Black hole 'halo' 14. What Happens if you fall into a Black Hole, 15. White Hole Escape, 16. Tidal disruption, 17. Black Holes in our Galaxy

　　结论

　　考虑到我们的星系拥有1亿个恒星质量的黑洞，而我们自己的星系，银河系，其中心就有一个超质量的黑洞，它很大，而它就处在水星的轨道内。也许，是我们开始更多地了解这些神秘现象的时候了。至少，以免我们会掉进去。

　　注释：1.死星的核。 2.各星系中心的黑洞。 3.恒星质量的黑洞。4. 超质量黑洞实际上是超质量的 5.中等质量的黑洞。 6.爱因斯坦的相对论 7相对论和量子理论 8 时空定义。9.引力波检测 10.黑洞光环。11 意大利面条化 12.人马座A 13.黑洞光环14. 如果你跌入黑洞会发生什么 15 白洞逃逸 16 潮汐扰动 17. 我们银河系的黑洞